#3.1.1 if语句
age = 5
if age >= 3:
    print("可以上幼儿园了")

#3.1.2 if...else语句
u_name = input("请输入用户名：")
pwd = input("请输入密码：")
if u_name == "admin" and pwd == "123":
    print("登录成功！即将进入主页面。")
else:
    print("您输入的用户名或密码错误，请重新输入。")

#3.1.1 if...elif...else语句
score = int(input("请输入您的会员积分："))
if score == 0:
    print("注册会员")
elif 0 < score <= 2000:
    print("铜牌会员")
elif 2000 < score <= 10000:
    print("银牌会员")
elif 10000 < score <= 30000:
    print("金牌会员")
else:
    print("钻石会员")
